Looper mechanism for sewing machines



May 30, 1939.

A. H. DE VOE LOOPER MECHANISM FOR SEWING MACHINES Filed Sept. 29, 1938 I gwuc rvbo'n Patented May 30, 1939 UNITED STATES PATENT OFFICE LOOPER MECHANISM FOR SEWING MACHINES Application September 29, 1938, Serial No. 232,249

8 Claims.

This invention relates to looper-actuating mechanism for chain-stitch sewing machines and has for an object to provide a looper-actuating mechanism which is simple in construction, light in weight and operable at ultra high speeds of the order of 9000 stitches per minute.

With the above and other objects in view, as will hereinafter appear, the invention comprises the devices, combinations and arrangements of parts hereinafter set forth and illustrated in the accompanying drawings of a preferred embodiment of the invention, from which the several features of the invention and the advantages attained thereby willbe readily understood by those skilled in the art.

According to the preferred embodiment of the invention, the looper is mounted on a loopercarrier which is pivotally connected at one end to a crank-pin working in an inclined cylindrical bearing in the head of a rotary drive-shaft. The axis of the pivotal connection betwen the loopercarrier and crank-pin is transverse to the longitudinal axis of the crank-pin, so that, as the drive-shaft rotates, the gyratory movement imparted by the inclined cylindrical bearing to the crank-pin causes the looper-carrier to partake of racking and bodily endwise movements, giving to the looper its loop-seizing and needle-avoiding movements. The looper-carrier is slidablysupported near the position of the looper by a bearing block which, in turn, is supported for universal tilting movements by and relative to a bearing support adjustably mounted on the machine bed. The universally mounted bearing which slidably supports the looper-carrier, permits the latter to spring, snake and whip under the stresses of ultra high speed operation, without cramping any of its bearings.

The invention will be better understood by referring to the accompanying drawing, of which Fig. 1 is a perspective view of the preferred embodiment of the present looper mechanism. Fig. 2 is an end elevation, Fig. 3 a top plan view and Fig. 4 a front elevation of the mechanism. Fig. 5 is a disassembled perspective view of the looperbar and the universally tiltable bearing-support therefor and Fig. 6 is a sectionon the line 6-6, Fig. 2.

The sewing machine is constructed with a bed I having a bearing lug 2 in which is mounted the bearing bushing 3 for the rotary drive-shaft 4 having at one end a conical shaft-head 5 which is formed with a hollow cylindrical bearing 6 the longitudinal axis of which is inclined to and coplanar with the longitudinal axis of the driveshaft 4.

Journaled in the bearing 6 is the crank-pin I having at its free-end a head 8 which is slotted at 9 to receive one end of the looper-carrier bar 10 in which is fixed the transverse pivot-pin H journaled in the bearings l2, 12 in the head 8'.

The looper-bar 10 is'formed at its opposite end with a cylindrical portion I3 which is rockably and endwise slidably supported in the bearing block [4 constituting the head of a rock-shaft l5 Journaled horizontally in the bearing sleeve 16. The bearing sleeve I6 is carried by the head ll of a rock-shaft l8 which is journaled vertically in a bearing-supporting block [9 secured by the screw 20 to a block 2-! mountedon the bed I The blocks l9 and 2| have a rib-and-groove positioning connection 22, Fig. 2, which extends in a direction parallel tothe axis of the drive-shaft 4'; By loosening the screw 20, the block l9 may be adjusted in a direction parallel to the axis of the drive-shaft 4.

The crank-pin 1 has secured thereto a collar 23 which works in a slot 24 in the conical shafthead 5. By loosening the collar 23 on the crankpin 1, the latter may be adjusted lengthwise of the bearing 6 to vary the amplitude of the sidewise motion imparted to the looper 25 which is mounted on the looper-bar Ill. The looper 25 cooperates, as usual, with the reciprocatory eyepointed needle 26; the looper advancing atone sideof the needle in seizing a needle-loop, then shifting sidewise and returning at the other side of the needle-path, so that the descending needle may enter a loop of the looper-thread in the formation of the conventional two-thread chainstitch.

By mounting the looper on a slender looperbar which is light in weight and is supported at one end by a universally tilting bearing and driven at its other end by an inclined crank connection with a rotary shaft, there is produced a mechanism which may be operated at very high speeds. The looper-bar may spring, snake, flex or Whip without cramping any of the bearings. This is a desirable attribute of a high speed mechanism.

The invention is not limited to a thread-carrying looper as it is obviously adaptable to drive any sewing machine looper-blade to which loopseizing and loop-shedding movements are to be imparted. The sidewise or needle-avoiding movements may or may not be had, depending upon the working position of the crank-pin 1 in its bearing 6. If this position is such that the axes of the pivot-pin II and shaft 4 intersect, there will be no needle-avoiding movement imparted to the looper.

The provision of the universally tiltable bearing support M for the looper-bar l0, in combination with the adjustable crank-pin 1, permits the amplitude of the side motion of the looper 25 to be adjusted by shifting the crankpin 1 relative to the collar 23 which is releasably secured to it.

Having thus set forth the nature of the invention what I claim herein is:

1. In looper mechanism for sewing machines, the combination with a rotary shaft and shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylin drical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, and a universally tiltable bearing slidably supporting said looper-carrier at a point spaced from said crank-pin head.

2. In looper mechanism for sewing machines, the combination with a rotary shaft and shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylindrical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, a universally tiltable bearing slidably supporting said looper-carrier at a point spaced from said crank-pin head, and means whereby the working position of said crank-pin in said cylindrical bearing may be shifted axially of the latter.

3. The combination with a rotary shaft and shaft-head having a cylindrical bearing inclined to the axis of said shaft, of a crank-pin journaled in said bearing, a looper, a looper-carrier bar pivoted at one end to said crank-pin on an axis transverse to the longitudinal axis of said crankpin, and a universally tiltable bearing slidably supporting the other end of said bar.

4. In looper mechanism for sewing machines, the combination with a rotary shaft and shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylindrical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, a bearing support, a universally tiltable bearing carried by said support and slidably supporting saidrlooper-carrier, and means whereby said bearing support may be shifted relative to said shaft-head.

5. In a sewing machine, a looper, a carrier on which said looper is fixedly mounted, a universally tiltable bearing in which said carrier is rockably and endwise slidably supported, a crank-pin to which said carrier is pivotally connected on an axis transverse to the longitudinal axis of said crank-pin, and a rotary drive-shaft having a head formed with a hollow cylindrical bearing in which said crank-pin is journaled, said bearing having its longitudinal axis inclined to the axis of revolution of said drive-shaft.

6. In looper mechanism for sewing machines, the combination with a rotary shaft and shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylindrical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, a universally tiltable bearing slidably supporting said looper-carrier at a point spaced from said crank-pin head, and means whereby the axis of the pivotal connection between the head of said crank-pin and said looper-carrier may be shifted to vary its distance from the axis of said rotary shaft and thus vary the amplitude of the sidewise or needle-avoiding motion of the looper.

'7. In looper mechanism for sewing machines,

the combination with a rotary shaft and. shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylindrical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, a universally tiltable bearing slidably supporting said looper-carrier at a point spaced from said crank-pin head, and means to prevent said crank-pin from moving endwise in and relative to said cylindrical bearing.

8. In looper mechanism for sewing machines, the combination with a rotary shaft and shafthead formed with a hollow cylindrical bearing the axis of which is inclined to the axis of said shaft, of a crank-pin journaled in said cylindrical bearing and having a head, a looper, a looper-carrier pivoted to said crank-pin head on an axis transverse to the longitudinal axis of said crank-pin, a universally tiltable bearing slidably supporting said looper-carrier at a point spaced from said crank-pin head, and a collar fixed to said crankpin and coacting with said shaft-head to prevent endwise movement of said crank-pin in and relative to said cylindrical bearing.

ALBERT H. DE VOE. 

